Your stc tv subscription comes with multiple device access depending on your subscription plan.
Mobile app - If you are trying to sign into mobile app and see this error on "My devices" screen, please delete one of the listed devices. As soon you delete a device, you will be automatically signed in.
Website: Please close the “maximum devices reached” error message and check "My Device" section. Delete a device by clicking the button next to the device, the page will automatically refresh after that and you will be automatically signed in.
Set-top box or Smart TV app – If you are trying to sign into TV application and see this error, please choose “Delete Device”. You will be directed to “My device” screen where you can delete any of the listed devices.
*Please note that you can delete a device after 30 days of use.